FIG. 1 is a view schematically illustrating the whole construction of a conventional dish washer, FIG. 2 is an exploded perspective view fully illustrating a drive unit of the dish washer shown in FIG. 1, FIG. 3 is a top view illustrating a flow channel structure of a filter housing shown in FIG. 2, and FIG. 4 is a sectional view illustrating the flow of wash water in the drive unit shown in FIG. 2 during a washing operation.
FIG. 5 is a top view illustrating the flow of wash water in the filter housing shown in FIG. 2 during a washing operation, and FIG. 6 is a top view illustrating the flow of wash water in the filter housing shown in FIG. 2 during a draining operation.
First, the schematic structure of a conventional dish washer will be described with reference to FIG. 1.
The conventional dish washer is constructed in a structure in which upper and lower washing arms 4 and 5, upper and lower racks 6 and 7, and a drive unit 10 are mounted in tub 1.
To the drive unit 10 are connected upper and lower connection pipes 2 and 3, through which wash water is supplied to the upper and lower washing arms 4 and 5, respectively, and a drainage hose 9, through which the wash water is drained. The upper and lower washing arms 4 and 5 are connected to the upper and lower connection pipes 2 and 3, respectively. The upper rack 6 is mounted above the upper washing arm 4, and the lower rack 7 is mounted above the lower washing arm 5.
The upper and lower washing arms 4 and 5 are rotatably mounted above the drive unit 10. The respective washing arms 4 and 5 are provided with injection holes, through which wash water is injected toward the corresponding racks. In addition, the lower washing arm 5 is provided with injection holes, through which wash water is injected toward the drive unit 10 such that food wastes are removed from a filter of the drive unit 10 by the injected wash water.
Next, the structure of the drive unit of the dish washer will be described in detail with reference to FIG. 2.
The drive unit 10 includes a sump 20 for receiving wash water, a heater 30 mounted at the sump 20 for heating the wash water, a washing pump 41 and 42 mounted at the sump 20 for pumping the wash water, a drainage pump 51 and 52 mounted at the sump 20 for draining the wash water, and a filtering unit for guiding some of the pumped wash water to the washing arms 4 and 5 (see FIG. 1) and filtering the remainder of the pumped wash water.
The sump 20 has a wash water receiving part 21, which is a space for receiving the wash water, and a drainage chamber 22 partitioned from the wash water receiving part 21. To the outside of the wash water receiving part 21 is mounted a flow channel control unit 25. A flow channel control valve 26 is axially coupled to the flow channel control unit 25.
The washing pump includes a washing motor 41 mounted to the bottom of the sump for generating a driving force, and an impeller 42 mounted in the filtering unit for pumping the wash water. To a shaft of the washing pump 41 is axially coupled a disposer 45 that is rotatable to crush food wastes. Above the disposer 45 is disposed a screen 46 having a predetermined mesh for filtering out large particles of food wastes.
The drainage pump is mounted at the drainage chamber 22. The drainage pump includes a drainage motor 51 and an impeller 52.
The filtering unit includes a pump housing 60 having a space where the impeller 42 is mounted, a filter housing 70 mounted such that the filter housing 70 covers the top of the pump housing 60, and a cover 80 mounted such that the cover 80 covers the top of the filter housing 70 and the top of the sump 20. The pump housing 60 is disposed at the bottom of the filter housing 70, and the cover 80 is disposed at the top of the filter housing 70.
The filter housing 70 has a filth collection chamber 75. The filth collection chamber 75 has a drainage pipe 75a, which communicates with the drainage chamber 22. The drainage pipe 75a protrudes downward by a predetermined length from the bottom of the filter housing 70. Consequently, the drainage pipe 75a is located in the drainage chamber 22 at the time of assembling the drive unit.
The cover 80 has a filter 81, which is disposed corresponding to the filth collection chamber 75 of the filter housing 70, and a plurality of collection holes 82 formed outside the filter 81. The collection holes 82 communicate with the sump 20.
Hereinafter, the filter housing 70, in which the flow channel control valve 26 is mounted, will be described in more detail with FIGS. 2 and 3, particularly FIG. 3.
The filter housing 70 includes a wash water introduction part 72 constructed such that wash water pumped by the impeller is introduced to the wash water introduction part 72, and main flow channels 73a and 73b and a sampling flow channel 74 connected to the wash water introduction part 72. The filth collection chamber 75 is connected to the sampling flow channel 74. At the drainage pipe 75a of the filth collection chamber 75 is mounted an opening and closing valve for discharging the wash water and the food wastes from the filth collection chamber 75 to the drainage chamber 22 (see FIG. 2) at the time of a draining operation.
In the above description, the sampling flow channel 74 is a flow channel formed to continuously filter out foreign matter contained in the wash water collected in the sump 20 using some of the wash water introduced to the wash water introduction part 72.
The flow channel control valve 26 is rotatably located in the wash water introduction part 72 of the filter housing 70 for opening and closing the main flow channels 73a and 73b. The flow channel control valve 26 is axially coupled to the flow channel control unit 25 (see FIG. 2) mounted at the sump 20. At the edge of the flow channel control valve 26 is formed an opening and closing rib 26a for opening and closing the main flow channels 73a and 73b. 
Now, the operation of the dish washer with the above-stated construction will be described.
The dish washer performs sequentially or selectively a preliminary washing operation, a main washing operation, a rinsing operation, a heating-rinsing operation, and a drying operation so as to wash dishes. Between the respective operations, a draining operation is performed. Hereinafter, the main washing operation and the draining operation will be described.
When the main washing operation is initiated, the washing motor is driven, and therefore, the impeller 42 is rotated. As a result, as shown in FIG. 4, the impeller 42 pumps wash water (containing detergent) from the sump 20 to the wash water introduction part 72 (see FIG. 3) of the pump housing 60.
At this time, the flow channel control unit 25 is rotated. As a result, the flow channel control valve 26 selectively opens one of the main flow channels 73a and 73b under the control of a microprocessor. For example, as shown in FIG. 5, the flow channel control valve 26 opens the main flow channel 73a. Although not shown, however, the flow channel control valve 26 may simultaneously open both the main flow channels 73a and 73b. That is, the opened state of the main flow channels is changed depending upon the rotating positions of the flow channel control valve 26.
Consequently, most of the wash water introduced into the wash water introduction part 72 is supplied to both the upper and lower washing arms 4 and 5 or one of the upper and lower washing arms 4 and 5 through the opened one(s) of the main flow channels 73a and 73b under the control of the flow channel control unit 25 based on the microprocessor. On the other hand, the remainder of the wash water is supplied to the filth collection chamber 75 through the sampling flow channel 74.
The flow channel control valve 26 may be controlled such that the two main flow channels 73a and 73b are simultaneously opened, and therefore, the wash water is supplied to both the upper and lower washing arms 4 and 5, such that only one of the main flow channels 73a and 73b is opened, and therefore, the wash water is supplied to one of the upper and lower washing arms 4 and 5, or such that the two main flow channels 73a and 73b are alternately opened, and therefore, the wash water is alternately supplied to the upper and lower washing arms 4 and 5.
On the other hand, some of the wash water is always supplied to the sampling flow channel 74 irrespective of which main flow channel is opened by the flow channel control valve 26. This is because the wash water must be continuously supplied to the sampling flow channel 74 in order to continuously filter out foreign matter from the wash water.
The wash water supplied to the filth collection chamber 75 through the sampling flow channel 74 overflows through the filter 81 disposed above the filth collection chamber 75. At this time, the filter 81 filters out foreign matter from the wash water.
The wash water filtered during the overflow and the wash water injected through the upper and lower washing arms 4 and 5 and having fallen to the cover 80 is reintroduced into the sump 20 through the collection holes 82.
When the wash water flows through the sampling flow channel 74 for a short period of time, the amount of wash water flowing through the sampling flow channel 74 is small, and therefore, the filtering effect of the wash water accomplished through the sampling flow channel is insignificant. According to the present invention, however, the wash water continuously flows through the sampling flow channel 74 for a relatively long period of time during the main washing operation, and therefore, most of the wash water is substantially filtered.
After the washing operation is completed, a draining operation is initiated.
When the draining operation is initiated, the drainage pump 51 and 52 is driven. At this time, wash water and food wastes in the sump 20 are introduced to the drainage pump 51 and 52 due to a suction force of the drainage pump 51 and 52. At the same time, as shown in FIG. 6, wash water and food wastes in the filth collection chamber 75 are also introduced to the drainage pump 51 and 52 through the drainage pipe 75a. The wash water and the food wastes introduced to the drainage pump 51 and 52 are discharged to the outside through the drainage hose 9 (see FIG. 1).
However, the conventional dish washer has the following problems.
First, the dish washer has a problem in that only some of the pumped wash water is injected through the washing arms, and therefore, the amount of wash water substantially injected to wash dishes is considerably reduced, whereby the washing efficiency of the dish washer is lowered. Also, the wash water is pumped in consideration of the amount of wash water circulating through the sampling flow channel, and therefore, it is needed to increase the capacity of the washing pump such that the amount of the injected wash water is sufficiently maintained.
Second, it is needed to consider the amount of wash water to be sufficiently injected to the dishes through the washing arms, the amount of wash water filtered while circulating through the sampling flow channel, and the amount of wash water injected from the lower washing arm to the filter so as to remove the food wastes from the filter. As a result, the amount of wash water substantially needed during the washing operation of the dish washer is considerably increased.
Third, the wash water pumped from the sump is directly introduced into the filth collection chamber through the sampling flow channel. As a result, a large amount of filth is introduced into the filth collection chamber, and therefore, the filter of the cover is clogged. Also, when the filter is clogged, large water pressure is applied to the filth collection chamber with the result that the wash water in the filth collection chamber is drained through the drainage hose, and therefore, the wash water is wasted. Furthermore, fatigue is accumulated in the filter, and therefore, the filter may be deformed.
Fourth, when the wash water is wasted as described above, it is needed to replenish wash water. Also, when a heating-washing operation is performed, the replenished wash water must be heated by the heater. Consequently, the consumption of wash water and power is unnecessarily increased.
Fifth, the sampling flow channel and the filth collection chamber are separately formed to filter the wash water. Consequently, the flow channel of the wash water is complicated. In addition, as the flow channel is complicated, wash water pumping pressure is considerably decreased. As a result, it is needed to use a washing pump having an increased capacity.
Sixth, the washing pump is mounted in an upright driven fashion, the disposer is mounted to the shaft of the washing pump, and the filth collection chamber is mounted above the pump housing. As a result, the structure of the drive unit is complicated, and the height of the drive unit is greatly increased. Otherwise, it is needed to reduce the inner space of the sump. Furthermore, as the size of the drive unit is increased, the capacity of the tub is relatively decreased.
Seventh, the flow channel of the dish washer is complicated, and food wastes are left in the filth collection chamber and the filter during the drainage operation of the dish washer. As time passes, the leftover food wastes go rotten in the dish washer, thereby generating a bad smell. Furthermore, when the food wastes are left in various flow channels, such as the filth collection chamber, it is very difficult to remove the food wastes.